Carbons produced from known organic compounds 2. Anthracene-biphenyl and phenanthrene- biphenyl systems

Carbonization of binary mixtures of anthracene biphenyl and penanthrene bipheny

Effective constructions in plethysms and Weintraub's conjecture

We give a short proof of Weintraub's conjecture by constructing explicit highest weight vectors in the symmetric power of an even exterior power

Distribution of phytoplasma in grapevines in the Golan Heights, Israel, and development of a new universal primer

Our survey, made in 1999 and 2000, sampled 4 of the most prevalent grapevine cultivars in northern, central and southern regions of the Golan Heights. There were significant differences in the levels of phytoplasma infection between different sub-regions of the Golan Heights; highest levels were found in the south, followed by the center, and the lowest levels in the north. Stolbur was found to be the predominant phytoplasma (~70 %), although aster yellow (~11 %), western-X (~5 %) and mixtures of two phytoplasmas (13 % of all infections, 90 % of which involved Stol and AY) were also found. Prior research on phytoplasmas of grapevines in Israel involved the use of two sets of universal primers. Primers were developed specifically for phytoplasmas occurring in Israel in which there were homologies of 90,85 and 78 % for Stol,AY and W-X phytoplasmas, respectively.

Evidence for Accretion in the High-resolution X-ray Spectrum of the T Tauri Star System Hen 3-600

We present high-resolution X-ray spectra of the multiple T Tauri star system Hen 3-600, obtained with the High Energy Transmission Grating Spectrograph on the Chandra X-ray Observatory. Two binary components were detected in the zeroth-order image. Hen 3-600-A, which has a large mid-infrared excess, is a 2-3 times fainter in X-rays than Hen 3-600-B, due to a large flare on B. The dispersed X-ray spectra of the two primary components overlap spatially; spectral analysis was performed on the combined system. Analysis of the individual spectra was limited to regions where the contributions of A and B can be disentangled. This analysis results in two lines of evidence indicating that the X-ray emission from Hen 3-600 is derived from accretion processes: line ratios of O VII indicate that the characteristic density of its X-ray-emitting plasma is large; a significant component of low-temperature plasma is present and is stronger in component A. These results are consistent with results obtained from X-ray gratings spectroscopy of more rapidly accreting systems. All of the signatures of Hen 3-600 that are potential diagnostics of accretion activity -- X-ray emission, UV excess, H-alpha emission, and weak infrared excess -- suggest that its components represent a transition phase between rapidly accreting, classical T Tauri stars and non-accreting, weak-lined T Tauri stars.Comment: latex, 27 pages, 12 figures, 6 tables; accepted by Ap

The Coronal X-ray Spectrum of the Multiple Weak-Lined T Tauri Star System HD 98800

We present high-resolution X-ray spectra of the multiple (hierarchical quadruple) weak-lined T Tauri star system HD 98800, obtained with the High Energy Transmission Gratings Spectrograph (HETGS) aboard the Chandra X-ray Observatory (CXO). In the zeroth-order CXO/HETGS X-ray image, both principle binary components of HD 98800 (A and B, separation 0.8'') are detected; component A was observed to flare during the observation. The infrared excess (dust disk) component, HD 98800B, is a factor ~4 fainter in X-rays than the apparently ``diskless'' HD 98800A, in quiescence. The line ratios of He-like species (e.g., Ne IX, O VII) in the HD 98800A spectrum indicate that the X-ray-emitting plasma around HD 98800 is in a typical coronal density regime (log n <~ 11). We conclude that the dominant X-ray-emitting component(s) of HD 98800 is (are) coronally active. The sharp spectral differences between HD 98800 and the classical T Tauri star TW Hya demonstrate the potential utility of high-resolution X-ray spectroscopy in providing diagnostics of pre-main sequence accretion processes.Comment: 11 pages, 5 figures; to appear in the Astrophysical Journal (Letters

Leadership of Health Innovation: Building an Innovative Health Organisation (A Mixed-Methods Study)

This thesis explores leadership styles associated with innovation in the National Health Service in England, drawing on a review of leadership theories and concepts, and comparing what is found with an organisation in the United States recognised as a high performer in this area. Although leadership has been studied extensively, most research has focused on the political and military spheres. More recent work has also examined the role of leadership in sectors such as manufacturing and technology, both areas where it is essential to encourage and nurture innovation. Yet, in the health sector, where innovation is now high on the health policy agenda in many countries, there is a paucity of research on how leadership can foster a culture of innovation. It cannot be assumed that leadership theories and concepts developed in other sectors will automatically apply to the health sector, given its many complexities and specificities, including multiple and sometimes competing objectives, such as the need to match technological advances with cost containment. Moreover, these objectives may vary in different settings, reflecting the contextual embeddedness of health systems. This research asks what leadership styles have been adopted by those working at senior leadership and management levels in organisations created to support innovation within the NHS in England. To place these findings in a broader context, these findings will be compared with those obtained from a leading health sector organisation identified as a global leader in innovation that served as the US Pilot Study for this research. It will relate these findings to theory and previous empirical research on leadership for innovation while exploring the application of these findings to the health sector. The research uses a mixed method approach, commencing with a review of the literature to identify leadership styles and critical appraisal of evidence associating different styles with the extent and nature of innovation, which in turn has informed development of an instrument to be used in a survey (quantitative element) of those in leadership roles. The instrument draws extensively on that used by Handy (1996) to assess organisational culture. The survey questions are linked to leadership theories and concepts identified in the literature review and seek to identify the leadership styles adopted in the organisations studied. The findings inform the qualitative phase of the study, in which interviews with key informants are used to interpret and understand the quantitative results. The study findings have been used to generate a ‘Leadership Framework’ for assessing leadership styles in organisations seeking to foster innovation in the NHS. This is based upon the leadership styles described in the literature and leadership theories and concepts driving health innovation and to a minor extent to those adopted in a successful innovator in the United States health sector. The research concludes by offering contextually appropriate recommendations based on theory and empirical evidence

Infrared Space Observatory Polarimetric Imaging of the Egg Nebula (RAFGL 2688)

We present polarimetric imaging of the protoplanetary nebula RAFGL 2688 obtained at 4.5 microns with the Infrared Space Observatory (ISO). We have deconvolved the images to remove the signature of the point spread function of the ISO telescope, to the extent possible. The deconvolved 4.5 micron image and polarimetric map reveal a bright point source with faint, surrounding reflection nebulosity. The reflection nebula is brightest to the north-northeast, in agreement with previous ground- and space-based infrared imaging. Comparison with previous near-infrared polarimetric imaging suggests that the polarization of starlight induced by the dust grains in RAFGL 2688 is more or less independent of wavelength between 2 microns and 4.5 microns. This, in turn, indicates that scattering dominates over thermal emission at wavelengths as long as ~5 microns, and that the dust grains have characteristic radii < 1 micron.Comment: 27 pages, 9 figures; to appear in the Astronomical Journal, May 2002 issu

Quiescent H2 Emission From Pre-Main Sequence Stars in Chamaeleon I

We report the discovery of quiescent emission from molecular hydrogen gas located in the circumstellar disks of six pre-main sequence stars, including two weak-line T Tauri stars (TTS), and one Herbig AeBe star, in the Chamaeleon I star forming region. For two of these stars, we also place upper limits on the 2->1 S(1)/1->0 S(1) line ratios of 0.4 and 0.5. Of the 11 pre-main sequence sources now known to be sources of quiescent near-infrared hydrogen emission, four possess transitional disks, which suggests that detectable levels of H$_2$ emission and the presence of inner disk holes are correlated. These H$_2$ detections demonstrate that these inner holes are not completely devoid of gas, in agreement with the presence of observable accretion signatures for all four of these stars and the recent detections of [Ne II] emission from three of them. The overlap in [Ne II] and H$_2$ detections hints at a possible correlation between these two features and suggests a shared excitation mechanism of high energy photons. Our models, combined with the kinematic information from the H$_2$ lines, locate the bulk of the emitting gas at a few tens of AU from the stars. We also find a correlation between H$_2$ detections and those targets which possess the largest H$\alpha$ equivalent widths, suggesting a link between accretion activity and quiescent H$_2$ emission. We conclude that quiescent H$_2$ emission from relatively hot gas within the disks of TTS is most likely related to on-going accretion activity, the production of UV photons and/or X-rays, and the evolutionary status of the dust grain populations in the inner disks.Comment: 12 pages, emulateapj, Accepted by Ap